The present invention relates to the use of non-contact, long-standoff, optically based inspection techniques for on-line inspection and process control of the e-beam manufactured workpieces, including composites and other advanced materials.
The present invention allows for the real-time inspection during e-beam processing of composites and related materials. In the prior art, such composite-based materials were routinely fabricated in so-called autoclave systems, which are size-limited and tend to be slow. More recently e-beams have been used to locally treat these materials by localized heating.
In the prior art, thermal wave imaging (TWI) has been used as a diagnostic technique to inspect workpieces, including composites and other advanced materials. See U.S. Pat. No. 4,874,251 to Thomas et al.
In the prior art, laser-based ultrasound (LBU) has also been used as a diagnostic technique to inspect what pieces, including composites and other advanced materials. See, for example, U.S. Pat. No. 5,760,904 to Lorraine et al.
The disclosures of U.S. Pat. Nos. 4,874,251 and 5,760,904 are hereby incorporated herein by reference.
E-beam processing holds a lot of promise since it can be used to manufacture large-area components at higher rates and with less energy than prior art autoclave systems. Given this robust manufacturing tool, the need for adequate process control becomes a critical issue. The use of the LBU and TWI for this process-control provides a number of advantages in that the e-beam used in the manufacture of a workpiece can also be used as an energy source for the LBU and/or TWI non destructive testing applications.
The present invention relates to a method of process control for e-beam fabrication of a workpiece, the method including the steps of: (i) impinging the workpiece with a e-beam during a manufacturing step in the manufacture thereof and (ii) simultaneously optically sensing the workpiece using thermal-wave imaging and/or ultrasound imaging techniques for process control, wherein the e-beam impinging the workpiece in accordance with step (i) above provides substantially all the energy needed to be added to the workpiece to perform the optical sensing of step (ii) above.
The present invention can greatly enhance the manufacturability (quality assurance, reliability, reproducability, etc.) for e-beam fabrication since the in-situ LBU and TWI diagnostics can yield quality assurance information at each step (e.g. as each pre-preg layer is processed) as well as provide feedback control to the e-beam to optimize its parameters (energy, focus, scan rate, etc.) for rapid and high quality e-beam manufacturing.